kernel patch for QEMU ?

kernel patch for QEMU ?

[Atsushi Nemoto]

Now I'm trying QEMU 0.8.1 on mips.

I found mips-test-0.1.tar.gz on QEMU download page and can run it
(thanks ths!), but I still can not run a kernel (current lmo git)
compiled by myself.  My kernel stops after the famous "Checking for
'wait' instruction...  available." message.

The mips-test-0.1 contains kernel 2.6.16-rc6.  Is this a stock
kernel.org's kernel or lmo's kernel?  Or is there any patch to make
kernel run on QEMU?

---
Atsushi Nemoto

Re: kernel patch for QEMU ?

[Ralf Baechle]

On Mon, May 15, 2006 at 01:08:46AM +0900, Atsushi Nemoto wrote:

> Now I'm trying QEMU 0.8.1 on mips.
> 
> I found mips-test-0.1.tar.gz on QEMU download page and can run it
> (thanks ths!), but I still can not run a kernel (current lmo git)
> compiled by myself.  My kernel stops after the famous "Checking for
> 'wait' instruction...  available." message.
> 
> The mips-test-0.1 contains kernel 2.6.16-rc6.  Is this a stock
> kernel.org's kernel or lmo's kernel?  Or is there any patch to make
> kernel run on QEMU?

Thiemo promised to send me patches so I hope it's only a matter of days
to get this fixed.

  Ralf

Re: kernel patch for QEMU ?

[Thiemo Seufer]

Atsushi Nemoto wrote:
> Now I'm trying QEMU 0.8.1 on mips.
> 
> I found mips-test-0.1.tar.gz on QEMU download page and can run it
> (thanks ths!), but I still can not run a kernel (current lmo git)
> compiled by myself.  My kernel stops after the famous "Checking for
> 'wait' instruction...  available." message.
> 
> The mips-test-0.1 contains kernel 2.6.16-rc6.  Is this a stock
> kernel.org's kernel or lmo's kernel?  Or is there any patch to make
> kernel run on QEMU?

This kernel is stock lmo except for a small patch which allows clean
system shutdown (qemu 0.8.1 does not have the counterpart to it).
The patch should be completely irrelevant otherwise.

However, later kernels try to access the CP0 pagemask register which
is R10000 specific, IIRC Qemu throws an Reserved Instruction exception
on accessing it.

I use a heavily patched version of Qemu which mostly supports mips32r2,
it also has better decoding of CP0 accesses. My current patchset is
available at http://people.debian.org/~ths/qemu/qemu-patches-bogus2,
it needs more work before it is ready for inclusion, and may be
completely useless for anybody else, since it works ATM only on powerpc
hosts.


Thiemo

Re: kernel patch for QEMU ?

[Atsushi Nemoto]

On Sun, 14 May 2006 19:21:51 +0100, Thiemo Seufer <ths@networkno.de> wrote:
> > The mips-test-0.1 contains kernel 2.6.16-rc6.  Is this a stock
> > kernel.org's kernel or lmo's kernel?  Or is there any patch to make
> > kernel run on QEMU?
> 
> This kernel is stock lmo except for a small patch which allows clean
> system shutdown (qemu 0.8.1 does not have the counterpart to it).
> The patch should be completely irrelevant otherwise.
> 
> However, later kernels try to access the CP0 pagemask register which
> is R10000 specific, IIRC Qemu throws an Reserved Instruction exception
> on accessing it.

Thanks.  I'm looking output of "git-diff linux-2.6.16-rc6" but still
failed to find relevant changes...

The stock QEMU 0.8.1 works ok with vmlinux-r1 in mips-test-0.1 so it
should be something different on kernel side.  Hmm...

---
Atsushi Nemoto

Re: kernel patch for QEMU ?

[Atsushi Nemoto]

On Mon, 15 May 2006 10:55:13 +0900 (JST), Atsushi Nemoto <anemo@mba.ocn.ne.jp> wrote:
> The stock QEMU 0.8.1 works ok with vmlinux-r1 in mips-test-0.1 so it
> should be something different on kernel side.  Hmm...

It seems the difference comes from configuration.  If I enabled
CONFIG_DEBUG_SPINLOCK, I can run a kernel compiled from current git
tree.  Also, if I used kernel-config in mips-test-0.1 and disabled
CONFIG_DEBUG_SPINLOCK, the kernel stops at the same place.  So I'm
quite sure the option affects qemu's behavior.  But no idea why ...

---
Atsushi Nemoto